Ticking upper valve covers

[FabianK]

Hello Forum,

I would like to hear your experiences on the subject of ticking in the upper valve cover area. It is very prominent on mine. i had a suspicion at first that it was the valves themselves. However, I checked the valve clearance and they are set correctly. I then recorded an audio file, isolated the ticking and determined the frequency. It is exactly the idle speed of the engine, which really only leads to one conclusion. It is the injectors, which are activated once per revolution. But I still find it surprising that they are so loud. I don't have a lot of comparisons, but I think mine ticks particularly loudly.
Can you also observe this with yours? Or is there another cause? By the way, the ticking is very identical on the left and right. The right side is a bit louder, but the fan doesn't shield anything.

Attached you can find the audio streams (mp3 files, are compressed in a zip). I recorded the sound directly in the engine compartment at the right valve cover. In the picture you can see the isolated frequency. If you look closely, there are several peaks on top of each other, which could be the individual injectors.

Greetings
Fabian

https://www.dropbox.com/scl/fi/6aimemd9gnz97wrifu2sk/Archiv.zip?rlkey=7ayvwa9gv44k114m3cel6dpk7&dl=0

[proporsche]

well? i tried to listen but this mp3 does not allow me to hear it..make a video

Ivan

[FabianK]

I zipped both audio streams.
Here are the links to the unpacked files. And additionally the whole video. Hope this works.

Original audiostream

https://www.dropbox.com/scl/fi/ugzlwiqs5zlsmqsai9icx/ungefiltert.mp3?rlkey=39p8bxksbit9eri2wfgbcz0ah&dl=0

Filtered audiostream

https://www.dropbox.com/scl/fi/w8sy0bqs4rwx8ejdtrzza/gefiltert.mp3?rlkey=zgxkep65msily3cqcj461syrx&dl=0

Video

https://www.dropbox.com/scl/fi/eym3m2924hioedtutss6d/IMG_0598.mov?rlkey=oa610u5iz91vxzbhh2sitb03u&dl=0

[walt]

"It is the injectors, which are activated once per revolution" I believe every other revolution on a 4 cycle.

[FabianK]

Hi, what do you mean with revolution on a 4 cycle?

[spuggy]

Originally Posted by walt

"It is the injectors, which are activated once per revolution" I believe every other revolution on a 4 cycle.

Yes, but Motronic (which I presume we're talking about here, although there are few clues in the thread so far - hint ) is batch fire.

Unlike sequential injection (requires cam sync signal, which Motronic doesn't have), with batch injection, when any injector needs to fire, they all fire - regardless of what stroke that individual cylinder is on, or where the piston is.

Video sounds like a motor with normal valve clearances to me.

[FabianK]

Oh sorry, didn‘t mention that. It is a 86’ 3.2 Carrera.
As far as I know Motronic opens all 6 Injection valves in a batch at the same time and every revolution when it gets signal from the crankshaft sensor.

[wazzz]

I think it sounds not too bad. You should hear mine, clicks even worse.

What did you use for recording? If you want to hear the injectors clicking, use a stethoscope or a wood stick and apply it to each injector. You'll find out if it follows the same speed as the clicking noise recorded.

[FabianK]

Yeah you hear even more prominent with a stick on the injectors. There is only little doubt that it comes from the injectors. I’m just wondering why it is that loud. When I rebuild my engine I also cleaned the injectors and after that they are even a little bit louder. Other 3.2 are quieter, at least the ones I heard…

[proporsche]

for me your valve adjustment need to be done-correctly ,way too noise..here is how is supposed to be...my 911

Ivan
btw : how did you adjust the valves?


https://www.youtube.com/watch?v=Out_PKGkYYY

[pmax]

Sounds fine to me. Loudness is relative, if everything else's quieter.

However, it does sound like Ivan could use a new PC !

[proporsche]

Originally Posted by pmax

Sounds fine to me. Loudness is relative, if everything else's quieter.

However, it does sound like Ivan could use a new PC !

Why do i need new PC?;-)))

[FabianK]

I cannot be the valves as the clicking is at the same frequency like the crankshaft. Valve ticking would be at half frequency.
I adjusted valves with 0.1mm and checked it twice…

[proporsche]

Originally Posted by FabianK

I cannot be the valves as the clicking is at the same frequency like the crankshaft. Valve ticking would be at half frequency.
I adjusted valves with 0.1mm and checked it twice…

Ok if you say..oh dear;-)..what is timing marks on your front pulley .is it original or something else?definitely noise engine..
here is another video ..just finished this engine(couple years back)
https://www.youtube.com/watch?v=Eym1f9xtXl4

Ivan

[proporsche]

one more comparison for you..finished this 911 engine couple of month ago -zero miles on it yet...
https://www.youtube.com/watch?v=vniHFvd7WSo

Ivan

[FabianK]

When I record the sound with your camera distance the ticking is also not prominent. Do you also have a video direct from the valve cover? Btw. Underneath the car you cannot hear any ticking.

It is the original pulley, there is no modification done with the engine. What I mean with frequency: when motor is running on idle speed, it is 880RPM. When you look at the picture you see that they’re also exactly 880 peaks per minute. Any noise from camshaft should be 440 times per minute, as camshaft turns with half speed.

In your first video you can also hear the same ticking in the background…

[proporsche]

Fabian..i`m an oldtimer 911 mechanic i do not go by any frequency.or anything else like that...yes for a trained ears there is always some noise(not one 911 sound the same as another) but your is way too much..anyway good luck..no harm done, just trying to help you that is all..
Ivan

[FabianK]

I appreciate your help and comments, Ivan. I’m not a mechanic but engineer and do data analytics everyday, that’s why I try to bring noises in correlation with frequencies and so on ��
What would you recommend me? I checked already valve clearance and that is ok. And when I listen with a screwdriver on the valve covers I hear nothing…

[proporsche]

all good here..what is the story with this engine? How many KM and e.t.c. the sound is on the right side what about the other side?As you said, nada on bottom right?How are your valve springs..if you have some broken any adjustment would not help....

[FabianK]

Engine has 210.000km. I did a fully rebuild 3000km ago due to broken head studs. I also reworked valve heads and springs are ok. Noise was before rebuild the same. Left side is also noisy but not that prominent. But as on left hand side there is the big fan housing I think it is a little bit more shielded. Under the car you hear nothing.
Except of the noise engine runs excellent.